Electrokinetic properties of wavellite and its floatability with cationic and anionic collectors

• Published in: Journal of colloid and interface science Vol. 361; no. 2; pp. 632 - 638
• Main Authors: Nunes, Aline Pereira Leite, Peres, Antônio Eduardo Clark, de Araujo, Armando Corrêa, Valadão, George Eduardo Sales
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 15.09.2011; Elsevier
• Subjects: Accumulators; Aluminum; Cationic; Chemistry; Collectors; Eletctrokinetic potential; Exact sciences and technology; Flotation; General and physical chemistry; Phosphorus; Surface chemistry; Surface physical chemistry; Wavellite; Wavellite; Collectors; Flotation; Eletctrokinetic potential; Phosphates; Ore; Electrokinetics; Iron; Potential; Mechanism; Chemical reduction; Interface properties; Precipitation; Amine; Collector; pH; Electrokinetic potential; Deprotonation; Surface complex; Starch; Ions; Phosphorus; Transition metal; Aluminium; Fatty acids; Adsorption; Sodium; Apatite; Protonation
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2011.06.014

The aluminum and phosphates species and the H+ e OH− ions will determine the wavellite-solution interface properties. Wavellite presents high floatability with amines in alkaline pH region. [Display omitted] . ► Microelectrophoretic technique was used for electrokinetic measurements of wavellite. ► The isoelectric point was achieved at the pH 4.5. ► Wavellite-solution interfacial properties are mainly determined by Al and P species. ► Wavellite’s floatability was higher with amines. ► Corn starch was not efficient depressant for wavellite. The reverse apatite flotation with fatty acids has been widely used for the reduction of phosphorus content of magmatic origin iron ores. However, the occurrence of phosphorus intensely disseminated as secondary minerals such as wavellite renders the anionic reverse flotation a challenge. Zeta potential measurements and microflotation tests of wavellite with the use of anionic and cationic collectors were carried out in this work. The wavellite’s IEP value was achieved at pH 4.5. Below the IEP value, the surface positively charged sites are made up of aluminum ions. The species H+,Al(OH)2+,Al(OH)2+,Al3+,OH-,H2PO4-,HPO42-, and PO43- play a role in the protonation and deprotonation reactions that will determine the wavellite-solution interface properties. The highest values of wavellite’s floatability under basic pH conditions were achieved in the presence of cationic collectors (1×10−4molL−1). The formation of surface complexes and the precipitation of insoluble salt of aluminum onto wavellite surface seems to be the most likely hypothesis for the chemical nature interactions between amines and wavellite. The surface formation of aluminum oleate on the wavellite’s surface seems to be the most probable hypothesis for the adsorption mechanism and the resultant high floatability of wavellite between pH 7.5 and pH 10.0 in the presence of sodium oleate (1×10−4molL−1). The results showed that the cationic reverse flotation of secondary phosphates is a promising route to reduce the phosphorus content of iron ores from deposits that underwent a supergene enrichment process, since wavellite floatability in the alkaline pH range, using amine as collector, was not significantly affected by the presence of corn starch.